1. Field of the Invention
The present invention relates to a calibration apparatus used in the fabrication of semiconductor devices. More particularly, the present invention relates to a calibration apparatus for inspecting and maintaining a probe station.
2. Description of the Related Art
In the manufacture of semiconductor devices, a plurality of chips is regularly arranged on a semiconductor wafer. Each of the chips includes a plurality of electronic devices, such as transistors, capacitors, resistors, and interconnections for connecting therebetween, and a plurality of bonding pads for connecting the electronic devices. The electronic devices are required to have proper physical structure and electrical interconnections so that the electronic devices are able to perform particular functions of the chip.
The electronic devices should be fabricated based on the particular design thereof so that the electronic devices are able to operate normally in various situations. Each step of the semiconductor fabrication process is, however, accompanied with factors inducing poor product quality, e.g., an incorrect process condition, faulty fabrication equipment, operator error, and others. Thus, chips fabricated by a deficient process step may unintentionally be inferior. In an effort to prevent a sale of inferior chips, a test step for testing the chips in a wafer level, which is called a “wafer test,” is required before packaging the chips. A subsequent test step of testing a packaged chip is called a “package test.” The wafer test is performed in order to analyze reasons of inferiority generated in the fabricating process and provide feedback based on the analysis to the fabricating process of semiconductor product.
A tester and a probe station are used to perform the wafer test. The tester is test equipment for analyzing whether, under an electrical input signal, the chips operate normally, and includes a computer with a built-in test program, electrical signal source units and electrical signal measurement units. The probe station is another test equipment for aligning and contacting a probe card with a plurality of probing needles on a predetermined position of the chip and electrically testing the chips. For performing these functions, the probe station includes the probe card, a wafer chuck for loading the wafer and a wafer chuck movement apparatus for three-dimensionally manipulating the position of the wafer chuck.
The probe station, particularly the wafer chuck, require periodic inspection and/or repair to perform the wafer test quickly and accurately. Inspection items, i.e., aspects that are to be inspected, required in connection with the probe station, and in particular, the wafer chuck, should include a horizontality of the wafer chuck, a temperature of the wafer chuck, a vacuum pressure of the wafer chuck, a tilt angle between the needle cleaning unit and the wafer chuck, a performance of a camera and a horizontality of the probe station. Conventionally, each of the inspection items is measured using a corresponding special tool in a corresponding special step. However, these conventional tools for each inspection item are difficult to prepare and maintain. Further, these conventional inspection tools require unnecessary inspection time.